Signatures on the old wall of the Instituut-Lorentz

Not all names could be deciphered.

The oldest signatures are from 1927, after the
Colloquium had moved from Ehrenfest's home to the
theory institute
on the Langebrug. Older signatures
are still preserved
in the guest bedroom of the Ehrenfest house on Witte Rozenstraat.

Here is a photograph of the old wall behind a blackboard, from 1950, before the wall was moved to the new Instituut-Lorentz on Nieuwsteeg. The deep horizontal scratch was made by a student of Ehrenfest after failing an exam, as recalled by Casimir in his biography.